I bought a new Futaba 6yg and plan to use it for a 4* 40 that I'm going to build. It's on channel 24 and the Futaba that came with my Avistar is on channel 46. Is it okay to get some new channel 24 crystals to fly the Avistar with? I want to be able to fly the Avistar on the better radio. I hope I didn't mangle this question too badly....... Thanks

You can change the crystal in the Futaba receiver to channel 24. There are "high" and "low" band receivers, and the one you have now is a high band receiver. Channel 24 is in the low band. Futaba recommends (actually, they are more insistent than recommends...) that you only use high band receivers in the high channles, and visa-versa. In reality, people have changed the receiver crystals accross the bands and have experienced no problems (that I am aware of... after doing searches on RCU too...). If the receiver range-checks OK after changing the crystal, just go fly.

In the US (where you are) only licensed people are allowed to change the crystal in the transmitter.

gus

glowplug.
you can do this no problem. Just buy a new crystal for your receiver in your avistar, insert, and enjoy! I did this with my own trainer when I bought a new radio and second plane. I have JR equipment, and the rx crystal cost me 13 dollars plus tax. I would imagine futaba wouldn't be that much different.

Just be carful when swapping out crystals. Although there is still some controversy about this it has been said that if you use a hitec crystal in a futaba RX or vise versa the multipiers in the crystals dont communicate properly with the receivers and there may be a compatability issue. Just an FYI when you do make the change its cheap insurance but I would stay with the same RX crystal as the brand RX you have.

Amen to that! Not worth the few dollars that you might save....

I also heard it both ways on(to far apart/no problem) hi and lo bands...
Even tho my Dazzler was switched from hi to low and I've had no
problems, but it was a free plane.. I wanted to switch the rec. in my
Avistar from 51 to 23 and use the flight pack for my next plane... But
I'm still not sure what to do.. I've checked and asked but it's sort of like
a 50-50 thing... And the key thing here is.... A flight pack, or just the
rec. is cheaper than a plane.... But most if not all agree to stay with the
same brand for the rec....

Futaba is the only make of RX that still does the "high/low band" thing. But there are differences inside the RX with the way futaba tunes it. So, if you put a "low band" crystal in to a "high band" RX or vice versa, there will be some loss of range. However, the big question is, will the range reduction be enough to notice in our typical "looks about right" "walk away from the model" range checks, and will it show up in the air.

I can certainly believe that while the range would be reduced, I can image it not being reduced enough to notice in the "real world" at least for some guys.

So, I personally wouldn't do it. (Of course, I personally wouldn't buy Futaba RX's for just this reason). However, if you want to do it, do a range check. If the range check works out fine, then you're good to go, and shouldn't have any trouble.

Oh, I'm not sure, but it's alos possible that you might be more open to outside or adjacent channel interferance. That won't show up in a range check, but could be messy later on. I'm just guessing on that though.

I guess the bottom line is sure, there are cheaper ways to go and yes this hobby can get expensive so to find ways to lessen the blow helps alot but, just because 95% of the time there isnt an issue doesnt mean that you couldnt fall victim to the other 5% at some point and I would much rather spend the $60 up front on a matching hi or low band Rec and matching Crystal than chance dropping a $400 to $600 or more out of the sky to save $15 in the long run. If I crash I would feel much better knowing it was operator error than a cheap mechanical failure due to my stubborness.

Well, maybe what I'll end up doing is getting a whole new receiver in the low band. Thing is they are about 60.00 bucks and that's not including a crystal. 12.00 more for those. Rats!

You don't need to stick with Futaba receivers. Look into a Hitech receiver, no banding, and they're cheaper (on average) than Futaba. I've got several and they all seem to work fine....

Andy

Well, I bought a crystal today and thought I would try a range check to see if it is functioning correctly. I've seen guys at the club doing range checks by turning on the RX & TX and walking about 100 ft. away. I did notice the control surfaces start to twitch at about 100 ft. but they had the transmitter antennea down. Is that how a range check is accomplished?

Yup. That's how a range check is done. If it got too weak at 100ft it's about right. Anything less than 50 feet is a no-go.

Sounds like you are A-OK.

gus

Thanks Gus. Well, I checked it out with my neighbor helping out and we got about 150 ft. before it started twitching. That's with the engine off. Do that sound about right?

Yea thats more than ok. You wont have any issues 150ft away with no antenna up is a long way to range test.

When range checking, it's also a good idea to check with the engine off, then check again with the engine running. If you notice much of a drop in range, you have some kind of problem that you should fix, like a loose or bad crystal or other issue. Many (most?) people don't do it, but it's a good idea.

Thanks guys. I'll get it out and range check again with the engine running.

Yes, do your range checks with the antenna collapsed; but, remember to never run your transmitter with the antenna down for more than a minute or two. With the antenna collapsed, the SWR (standing wave ratio) goes way up and there is excessive heating in the output stage of your transmitter. Extended operation with the antenna collapsed will be very unhealthy for your transmitter and, under some conditions, can cause it to catostrophically fail. At the very least, it will accelerate the mean time to failure. It is always good practice to keep the antenna FULLY EXTENDED except during brief periods for range tests.

i usually range check mine by running it down my private runway about 100ft w ant down and turn around and come back for takeoff. i figure if it acts funny i can pull the ant out and get it back. there is never anyone else around so this is the easy way. is there anything im not seeing?

A jump to/from 24-46 is out of spec according to the mfg. There's a reason for that, I'm sure, and it's not just to make more money in the service center.. (That's not a profit center for them) I learned the hard way that if I take care of my planes with the recommended maintanence, they tend to last longer!

The radio is a black box to me, and I don't even pretend to understand it.. But there might be more factors at play than just a simple range check with your TX... I dunno.. One scenario could be the poor tuning could could cause your RX to fail to reject somebody else's signal on another channel... Or combinations of channels.. This kind of stuff may not show up until it's too late. The point I'm trying to make is that you can't possibly range check under all conditions, and you may end up in a pickle, even if it seems to work today. Send it in and let them tune it. $30 tops with shipping, and it's cheap insurance. Retuning and a bench check isn't a bad idea to do annually anyway.

YMMV. Chuck

The taxi away and taxi back thing isn't something I'd do. It sounds good, but in the time from when you loose control until you get the antenna up, a lot can happen. I don't know about you, but I'm not physically able to pull the antenna and be messing with the sticks at the same time. (yes, I realize you don't have to get the antenna all the way up, just enoug to restore control, but still). If the throttle glicthed to full power, the plane could leap off the ground and either hit something, or catch a wing tip and damage the plane.

It's just safer to teather the plane so it can't go anywhere or damage itself or anything else, and walk a short distance.

illl take your advice montgue. i never thought of a throttle glitch that would be ugly. thats why i asked the question , ithought i might be missing something. its worked for 9 mos so ive been pretty lucky .

OK, i am confused so i emailed tony stillman at rc report, and he said that the high low band issue on a futaba rx is a non issue, his words, said you can put any DC xtal,( HUH), into a receiver, range check and go fly. So why the high, low band receiver difference? Thanks Dennis....

Tony knows his stuff. He probably has the largest RC radio repair shop outside of Hobby Services.

DC stands for "Dual Conversion" BTW. Any crystal you buy that is designed for your RX in question will be Dual Conversion.

Hope this helps, Chuck

Well I can't speak for all but my experience so far has been positive. I change out crystals and put the low crystal (24) into the high reciever and it worked just fine. In fact my instructor is on channel 25 and I was flying next to him on channel 24 with no problems at all. Again, I can't speak for others but it has worked well for me.

If you are switching from 24 to 46, your asking for trouble because your going between High and low bands The Futaba we page tells you this. 11-35 is low and 36-60 is high. You can change around with no problems within one side but cannot cross over. If you do this, you better send the whole thing TX and RX to get re tuned.

But going by some of the threads here, make sure you bring a garbage back out with you to brong that plane back in.